This application is based on application No. 10-180946 filed in Japan, the content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a digital camera using a taking lens used by cameras using media of different sizes and image sensing elements such as a CCD and the like, and specifically relates to a digital camera using a taking lens for cameras using silver halide film.
2. Description of the Related Art
In recent years, digital cameras have become popular replacements for cameras which use silver halide film in conjunction with advances in semiconductor and image processing arts. Such digital cameras basically take an optical image from a taking lens and subject the image to photoelectric conversion via image sensing element such as a charge-coupled device (CCD) or the like, subject the converted output data to image processing, and store the image data on a storage medium such as a memory card or the like.
A digital camera which makes practical use of the assets of the silver halide single lens reflex camera has been proposed during the popularization of the digital camera. This camera provides the body of a silver halide camera comprising a magazine at one end in the film length direction, compartment for the power source batteries E1-E4 at the opposite end, and a grip G, used directly as a camera body 2, as shown in FIGS. 8 and 9.
This camera is provided with a shutter button 9 on the top surface of the grip G of the camera body 2 provided with a viewfinder 3; a taking lens 301 for a single lens reflex camera is installed on the front mount 25, a quick return mirror M1 and focal plane shutter 26 and the like are provided behind the taking lens 301 in the optical axis direction, and a CCD 303 is disposed at a position on the optical axis near the film gate 29.
When the shutter button 9 is pressed, the quick return mirror M1 is rotated to the dashed line position in FIG. 9 so as to be retracted from the photographic optical path, and directly thereafter the focal plane shutter 26 is opened, the object image viewed through the finder 3 forms an image on the CCD 303, and the CCD 303 converts this image to an optical image via photoelectric conversion. The focus point of the taking lens 301 is automatically focused by an auto focus (AF) actuator 220 provided at a suitable location within the camera body 2.
As mentioned above, when a CCD receives light using a taking lens 301 of the silver halide single lens reflex camera, the size of the CCD and the size of the silver halide film must be equal, as shown in FIG. 8, to ensure the same field angle as the silver halide single lens reflex camera. A large CCD 303 equivalent to the aforesaid film is difficult to manufacture and produces an extremely poor yield in the current state of the art. Conversely, when a conventional small CCD 303, such as a xc2xd inch size, is used, the field angle is reduced because light only reaches the center area of the film frame, and an adequately wide angle photograph cannot be obtained.
To eliminate this disadvantage, it has been proposed to remove the back cover of the silver halide single lens reflex camera, and arrange the CCD 303 through a relay lens behind the focus point of the taking lens 301. According to this construction, an image formed at a certain position on conventional film is relayed via the relay lens, and reduced to a size matching the size of the CCD so as to form an image on the CCD.
In this construction, however, the camera body is elongated in the back, so as to make it extremely difficult to hold the camera, and increasing the susceptibility to so-called camera vibration and the like.
In view of the aforesaid information, an object of the present invention is to provide a digital camera that does not increase the size of the camera body even when constructed using a small type image sensing element.
These objects are attained by the digital camera of the present invention which uses the taking lens for a silver halide camera, comprises an optical system disposed between an install position of the taking lens and a focal plane of the taking lens; and an image sensing element disposed at a composite focus plane of the taking lens and the optical system.
Another digital camera of the present invention comprises: a mount on which exchangeable taking lens is installed; an optical system disposed between the mount and a focal plane of the taking lens; and an image sensing element disposed at a composite focus plane of the taking lens and the optical system.